1. Field of the Invention
The present invention relates to a Vibrio harveyi-specific binding Down syndrome cell adhesion molecule (Dscam), a method for identification thereof and a use thereof. A Dscam selected from V. harveyi-challenged shrimps includes an amino acid of SEQ ID NO:1 specifically binding to V. harveyi to eliminate or reduce V. harveyi for purposes of substantially lowering pathogenic growth.
2. Description of Related Art
For almost a century, the supply from capture fisheries goes on a downward trend due to the worsening overfishing phenomenon. Therefore, aquaculture may be the primary source of supply of aquatic food in the future. Shrimp farming industry began to develop since the 1980s. However, a lack of professional training and management concepts of breeding biosecurity leads to serious outbreaks of shrimp infectious diseases, e.g. vibriosis, shrimp white spot syndrome or the like, resulting in the collapse of the global shrimp farming industry. Vibrio harveyi is the most important pathogen that causes vibrio infectious diseases to shrimps or other various aquatic organisms. In order to get rid of such a predicament, prevention and treatment of shrimp infectious diseases are imperative.
Up to now, non-specific antibiotic or non-hypervariable antimicrobial peptide (AMP) is mostly used to reduce water microflora and enhance shrimp immunity in prevention and treatment of shrimp infectious diseases. For instance, U.S. Pat. No. 7,670,836, issued on 2 Mar. 2010, disclosed an antimicrobial peptide, monodoncin, which is isolated and purified from Penaeus monodon and is capable of being mass produced by molecular cloning techniques in a heterologous expression system, such as yeast. Monodoncin demonstrates a wide range of bacteriostatic and bactericidal effects on G (−) and G (+) bacteria as well as fungicidal activities, and can be used with conventional antibiotics in a “cocktail therapy” to improve the therapeutic effects of the conventional antibiotics. However, the foregoing antibiotic and AMP lack the feature of identifying the pathogen specifically, so it is likely to cause imbalance of water microflora and shrimp health. Furthermore, excessive use of antibiotics could not merely lead shrimps to drug resistance easily, but also seriously affect food safety.
Besides, there are other ways to prevent aquatic animals from pathogens, such as U.S. Pat. No. 7,807,144, issued on 5 Oct. 2010, disclosed an oral vaccine that includes a multiple-cell organism for use as food for an aquatic animal (e.g., a fish or a shrimp) to be vaccinated, and a method of multiple-cell organism encapsulating a single-cell organism or an antigen, wherein the single-cell organism has been transformed to express a substance (including recombinant antigen, DNA, RNA and saccharide) that can resist to disease and/or induce an immune response in the aquatic animals for promotion of aquatic animal immunity. However, some disadvantages still exist in the US patent i.e. complicacy in preparation, difficulties to predict the realistic response after transferring the nucleic acid in different aquatic animals, insufficient uptake, weak delivery and degradation in the digestive tract of nucleic acids.